THC won’t maintain .06 height, please help

This is what I followed.

Yes it moves freely, it also moves during the cut. I just finished the trouble shooting guide and it leads me to the height switch is getting wet. That seems feasible as it mainly fails when close to an edge. Though the erratic heights that I just watched make me think it’s a bigger issue.

It won’t let me add a video.

i would go off what the manual has. IDK why yours has 50psi for 16g when the manual has 55psi and that’s what I’ve been going by for the last 3 years with the cut60. I cut 14g at around 34A @ 55-60 psi 110ipm.

is the material flexing when it first touches down on IHS? that could be why it’s not accurate on cut height.

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I received this chart from primeweld today. I asked them for help and he provided this cut chart.

Yes it’s flexing some but shouldn’t THC account for that shortly after the cut starts? It cut the whole loop without adjusting.

so the up/down never illuminate? also on the DRO size, it should have “under Z axis control” or something like that effect when the Z axis is in control.

The only screen where the voltage is really outside of the 1.5v range is the first screen and the speed is well below the THC cutoff threshold.

The THC can only use the voltage reading to keep the torch at the height it was when the sample voltage was taken. It doesn’t know if that is .03" or .1". All it knows is that it read a voltage of 85.6v at the start of the cut and it will try to maintain that voltage.

Change your plunge rate in Sheetcam to at least 50IPM.

Post a picture of your torch mounted in the Z axis carriage.

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Torch mounting looks ok.

Thank you all for your ideas and help! I contacted Langmuir and they are sending me an upgraded version of the IHS switch. Thinking the liquid spraying on it was the majority of the issue.

I’m also upgrading my air. I’m going to add a dryer for o the system . See pic

Hopefully this fixes my issues. I’m also going to order shielded consumables eventually.

Thanks again,


We had a fair bit of discussion about that particular air drying set up here.

Regardless of what kind of air drying system you have you will need a desiccant cell to fully dehumidify the air before it enters the plasma unit.

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I have the motor guard prior to the plasma. Will that suffice? If not, what one would you suggest? Do you have a link?

I have a different brand of the dryer in the link but it is exactly the same.

the motorguard will remove some moisture but it does not compare to a desiccant cell.

here is a screenshot from the motorguard manual.

moto guard manual link.

here is a little more info on the air quality you are looking for.

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Motor Guard is not a dryer. It is a filter. It’s used, among other things, to filter out any powder or particulate that escapes a desiccant dryer and should be the last stage in your air supply to the Plasma Torch.

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Just a small note on the desiccant cell I linked, it does come with a small filter to stop desiccant from migrating down the line

You want desiccant and then a motor guard filter before air enters plasma cutter. The desiccant on mine is the big canister with site glass and motor guard 60 filter is the one with rubber airline hanging that plugs to plasma cutter. I have no water issues with this setup.

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How long can you cut before it re hires replaced desiccant?

Do you live in a humid location?

I live in lower Michigan, yes gets humid. Depends on how much cutting I do, average change out on desiccant is 1 month in summer and 2 months in fall through spring months. My compressor is 60 gallons with 3 hp motor single stage compressor. crack open Drain on tank 2 times throughout day to get rid of water.

i would add an aftercooler to the compressor. it greatly reduces the moisture in the tank and lines. But still ad a desiccant filter and motorguard right before the plasma.